Answer:
√2 d
Explanation:
[tex]d_{i}[/tex] = initial diameter of horizontal pipe = d
[tex]d_{f}[/tex] = final diameter of horizontal pipe
[tex]v_{i}[/tex] = initial speed of water = v
[tex]v_{f}[/tex] = final speed of water = (0.5) v
Using equation of continuity
[tex]d_{i}^{2} v_{i} = d_{f}^{2} v_{f}[/tex]
[tex]d^{2} v = d_{f}^{2} (0.5) v[/tex]
[tex]d^{2} = d_{f}^{2} (0.5) [/tex]
[tex]d_{f}[/tex] = √2 d